Bendix Commercial Vehicle Systems AD-9si Oil Coalescing Air Dryer - Manual (Page 12)

12
If, after bypassing the air dryer, the system pressure still
does not build, use the following procedure to remove,
clean, and reinstall the delivery check valve.
DELIVERY CHECK VALVE CLEANING PROCEDURE
(Note: This is only required if system pressure does
not build after temporary bypass is completed.)
Refer to Figure 7 throughout the following procedure.
De-pressurize the air brake system following the general
safety precautions outlined elsewhere in this document.
Also, always de-pressurize the air dryer purge reservoir
before servicing the air dryer by slowly loosening the fitting
that connects the air compressor discharge line to the air
dryer inlet port.
This procedure does not require removal of the Bendix
®
AD-9si ™ air dryer from the vehicle.
1. Remove the delivery check valve cover, located directly
above the delivery port (OUT 21).
2. The spring/delivery check valve can now be removed.
3. Remove and retain the o-ring from the check valve
body.
CLEANING & INSPECTION
1. Use a suitable solvent to clean all metal parts, and
use a cotton swab to clean the bore (Note: Do not use
abrasives or tools to clean the bore: any scratches
caused may necessitate replacing the Bendix AD-9si
air dryer.) Superficial external corrosion and/or
pitting is acceptable.
2. Clean the o-rings with a clean dry cloth. Do not use
solvents.
3. Inspect for physical damage to the bore and the check
valve seat. If the bore is damaged (by scratches
etc. that would prevent the delivery check valve from
seating), replace the AD-9si air dryer.
4. Inspect the delivery check valve, o-rings, etc. for wear or
damage. Replace, if necessary, using the check valve
replacement kit available at any authorized Bendix ®
parts outlets.
ASSEMBLY
1. Lubricate the smaller o-ring and check valve body with
a heavy duty lithium grease.
2. Install the o-ring on the check valve body by sliding the
o-ring over the set of four tapered guide lands. The
o-ring groove holds the o-ring in its correct location.
3. At the other end of the check valve body, the spring is
installed over the set of four straight guide lands. When
the spring has been pushed to the correct location, the
check valve body is designed to hold the end of the
spring in position: be sure that the spring is not loose
before continuing with this installation.
4. Install the assembled check valve body/o-ring/spring
in the delivery port so that the o-ring rests on its seat
and the free end of the spring is visible.
5. Grease the larger o-ring and install it onto the cover.
6. Replace the delivery check valve cover and torque to
720–840 in-lbs.
7. Before placing the vehicle back into service, check
to see that the system pressure now builds to full
operational pressure.